Answer:
4x + 3y = 1
Explanation:
(1, -1)
3x - 4y = 20 ---> 4y = 3x - 20 ---> y = 3/4 x - 5
so slope is 3/4
and perpendicular slope is m * 3/4 = -1
m = -4/3
line equation is y - y1 = m (x - x1)
y - (-1) = -4/3 ( x - 1)
y + 1 = -4/3 (x - 1)
3y + 3 = -4x + 4
4x + 3y = 1